1. Field of the Invention
The present invention relates to a barrier laminate, especially to a barrier laminate having excellent adhesiveness and having a low water vapor permeability, and also relates to a barrier film substrate comprising the barrier laminate and to a device such as an organic EL device (organic electroluminescent device) comprising it.
2. Description of the Related Art
Heretofore, a barrier film fabricated by forming a thin metal oxide film of aluminium oxide, magnesium oxide or silicon oxide on the surface of a plastic film is widely used for wrapping or packaging articles that require shielding from various gases such as water vapor or oxygen and for wrapping or packaging edibles, industrial articles and medicines for preventing them from being deteriorated.
Recently, in the field of liquid-crystal display devices and organic EL devices, plastic film substrates are being used in place of glass substrates that are heavy and readily cracked or broken. As applicable to a roll-to-roll system, plastic film substrates are advantageous in point of cost. However, plastic film substrates are problematic in that their gas-barrier property is not good as compared with that of glass substrates. Therefore, when a plastic film substrate is used in a liquid-crystal display device, then water vapor may penetrate into the liquid-crystal cell, thereby causing display failures.
For solving the problem, it is known to form a water vapor barrier layer on a plastic film, thereby using the resulting barrier film substrate. As such a barrier film substrate, there are known a plastic film coated with silicon oxide through vapor deposition (for example, see JP-B 53-12953, pp. 1-3), and a plastic film coated with aluminium oxide through vapor deposition (for example, see JP-A 58-217344, pp. 1-4). These have a water-vapor barrier level of 1 g/m2·day or so.
However, substrates for use in organic EL devices require a further higher water vapor barrier level. To satisfy the requirement, there have been reported a technique of forming a laminate of an organic layer and an inorganic layer as a barrier layer, thereby realizing a water vapor permeability of less than 0.1 g/m2·day (for example, see JP-A 2003-335880 and JP-A 2003-335820), and a technique of realizing a further lowered water vapor permeability of less than 0.01 g/m2·day (see U.S. Pat. No. 6,413,645).